A skin-care product company is expanding in Rowan County, adding 119 jobs, Gov. Bev Perdue’s office announced Monday. Ei Inc., which employs about 200 people in Kannapolis, develops and manufactures prescription, over-the-counter and therapeutic skin-care products, as well as some skin products for animals.The expansion will be tied to a partnership with KeraNetics, a regenerative medicine firm spun off from Wake Forest University that seeks to turn research and patents from the school’s Institute of Regenerative Medicine into commercial products. The company has announced military contracts to develop bone-regeneration and wound-healing products.